fix(background-agent): inherit parent session directory for background tasks

Background tasks were defaulting to $HOME instead of the parent session's
working directory. This caused background agents to scan the entire home
directory instead of the project directory, leading to:
- High CPU/memory load from scanning unrelated files
- Permission errors on system directories
- Task failures and timeouts

The fix retrieves the parent session's directory before creating a new
background session and passes it via the query.directory parameter.

Files modified:
- manager.ts: Look up parent session directory in launch()
- call-omo-agent/tools.ts: Same fix for sync mode
- look-at/tools.ts: Same fix for look_at tool
- sisyphus-task/tools.ts: Same fix + interface update for directory prop
- index.ts: Pass directory to sisyphusTask factory

src/index.ts

@@ -238,6 +238,7 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
   const sisyphusTask = createSisyphusTask({
     manager: backgroundManager,
     client: ctx.client,
+    directory: ctx.directory,
     userCategories: pluginConfig.categories,
     gitMasterConfig: pluginConfig.git_master,
   });